Snag shield for magnetic torque yarn tension device



March 10, 1910 AQCk 'KIR CHER .'3',499.6

SNAG SHIELD FOR MAGNETIC TORQUE YARN TENSION DEVICE.

' Filed NwLs. 1967 l8 l I all INVENTOR lo AUGUST C. K/RCHER BV J 67MATTORNEY United States Patent 3,499,615 SNAG SHIELD FOR MAGNETIC TORQUEYARN TENSION DEVICE August C. Kircher, Farmington, Conn., assignor toAllied Control Company, Incorporated, New York, N.Y., a corporation ofNew York Filed Nov. 8, 1967, Ser. No. 681,477 Int. Cl. B65h 59/16, 57/00U.S. Cl. 242-155 5 Claims ABSTRACT OF THE DISCLOSURE An invertedcone-shaped yarn snag shield is suspended below the rotatable capstan ofa magnetic torque yarn tension device to prevent yarn loops fromsnagging or becoming entangled on the base plate or supporting frame ofthe device. The base of the shield is substantially coterminous with thecapstan such that the conical surface of the shield extends to and isflush with the periphery of the capstan. The apex of the cone-shapedshield is displaced to the rear (toward the. mounting frame) of the lineof suspension of anyyarn loop that may form so that the yarn willride-up the conical surface of the shield and be repositionedautomatically to its proper running position about the peripheryof thecapstan in response to tension being applied to the yarn when movementof the yarn is initiated. a

FIELD OF THE INVENTION This invention relates to yarn tension devicesused in the textile industry to control the tension of traveling yarns.More particularly, this invention relates to a snag shield for such adevice to prevent snagging or entanglement of yarn loops on the base orsupporting frame of the device and to reposition automatically the yarnto the proper running position on the device when movement of the yarnis initiated.

BACKGROUND OF THE INVENTION Tension devices are used extensively in thetextile industry to maintain traveling yarns under controlled tension.For example, in the beaming of a warp, hundreds of yarn packages orspools are mounted in a creel and simultaneously drawn to the spool of abeaming machine. Unless the tension of all the yarns is substantiallyuniform, a defective warp can result when looser yarns pile up andoverlap tighter yarns. Accordingly, an individual tension device isutilized to control the tension of each yarn involved in a beamingOperation.

One type of tension device called an electromagnetic whor or magnetictorque yarn tension device has been found to be particularlyadvantageous by the textile industry because hundreds of the devices canbe electrically controlled by a single simple adjustment to select adesired tension for a large number of traveling yarns. Such devices aredescribed, for example, in U.S. Patents Nos. 2,705,362 and 2,738,937,which issued to R. H. Roughsedge on Apr. 5, 1955 and Mar. 20, 1956,respectively, and in U.S. Patent No. 3,034,744, which issued to J. E.Bancroft on May 15, 1962.

In the tension devices described in the above patents, the travelingyarn is fed through an inlet yarn guide, passed around the periphery ofa rotatable wheel or capstan, and fed out through an outlet yarn guide.The yarn is trained about the capstan in a manner to cause the capstanto rotate in response to the travel of the yarn. A drag, or brakingforce, is applied to the capstan by magnetic or electromagnetic means,which results in tension being applied to the traveling yarn.

3,499,615 Patented Mar. 10, 1970 Although tension devices of the typedescribed above have been used extensively by the textile industry foryears, one difliculty With the device continues to plague the industry.This difficulty is caused by the yarn loops occasionally formed when anoperative condition known as overrun occurs. Overrun is a conditionwhere the capstan continues to turn for a short interval after thetake-up spool for the traveling yarn is halted (i.e., the beamingoperation is stopped). This condition can result from an improper amountand/or improper timing of the control voltage applied to the tensiondevice during start up or shutdown of a textile operation. The overruncondition can also result from improper handling of the yarn byanoperator (i.e., jerking of the yarn during threading) while thetextile operation is halted. The overrun condition causes the yarn tobecome disengaged from the periphery of the capstan and to extend in aloop below the mounting plate or frame which supports the rotatablecapstan.

These yarn loops are the cause of considerable difliculty in that theyfrequently snag on the frame or base supporting the tension device andcause the yarn to break when the textile operation is resumed.Alternatively, the yarn will continue to run in the snagged conditionresulting in an excessive tension being applied to the yarn.Furthermore, when the yarn continues to run in the snagged condition, itis subjected to scoring or abrasion by the rough yarn contact area andfrequently is discolored by the metal removed from the frame or baseupon which the yarn is snagged.

To cope with the difiiculties described above, it is now necessary tomake a visual inspection of each tension device involved in a textileoperation prior to initiation of the operation to determine that eachyarn is properly positioned on its tension device and that no yarn loopsare present. It will readily be appreciated that this is time consumingand costly because as many as 1200 to 1400 tension devices may beutilized on a single machine. Furthermore, this inspection must berepeated each time the textile operation is halted, and hencesignificantly increases the down-time of the operation. This, of course,results in increased costs. In the event that a yarn loop of the typedescribed above is detected, the operator must remove the excess yarncausing the loop and reposition the yarn to its proper running positionaround the periphery of the capstan. Thus, each yarn must be handledindividually by the operator, which further increases the down-time ofthe operation.

SUMMARY OF THE INVENTION It is an object of the present invention toeliminate the above-described difficulties experienced with magnetictorque yarn tension devices.

It is a specific object of the invention to prevent yarn loops fromsnagging or becoming entangled on the base or framework supporting ayarn tension device of the type described above when movement of theyarn is initiated.

It is a further specific object of the invention to repositionautomatically the yarn suspended in a loop to the correct runningposition about the periphery of the capstan of a yarn tension device ofthe type indicated above in response to movement of the yarn.

The foregoing and other objects are attained in an illustrativeembodiment of the invention which comprises an inverted cone-shapedshield suspended below the rotatable capstan of a yarn tension device ofthe type described above. The base of the shield is substantiallycoterminous with the capstan such that the conical surface of the shieldextends from its apex to and is substantially flush with the peripheryof the capstan. The axis of the conical shield is at an angle withrespect to the capstan (viz, the base of the cone) such that the apex ofthe cone-shaped shield is displaced to the rear (toward thesupportingframe of the tension device) of the line of suspension of anyyarn loop that may form.

A yarn loop caused by the overrun condition described above or byimproper y'arn handling is, in and of itself, harmless and causesdifliculties only when it snags or becomes entangled on the supportingframe of the yarn tension device. Thus, in accordance with an aspect ofthe present invention, yarn loops are prevented from snagging orbecoming entangled on the base or framework supporting the tensiondevice by the coneshaped shield, and any yarn loop which does formremains harmless.

In accordance with another important feature of the present invention,not only is a yarn loop prevented from snagging on the base of thetension device, but concomitantly in response to travel of the yarn, theyarn loop is eliminated and the yarn is automatically repositioned tothe proper running position about the periphery of the capstan of thetension device. The displacement of the apex of the cone-shaped shieldto the rear of the line of suspension of any yarn loop that formsensures that the yarn will not locate itself on the back (towardmounting frame) of the cone-shaped shield, but instead of rideup thefront (away from mounting frame) of the conical surface of the shieldand onto the periphery of the capstan of the device when tension isapplied as a result of movement of the yarn.

Advantageously, the provision of shields in accordance with the presentinvention on magnetic torque yarn tension devices of the type indicatedabove eliminates the need for a visual inspection of each of the devicesfor possible yarn loops each time a textile operation is halted, andalso eliminates the need for individual handling of each yarn that mayhave formed into a yarn loop.

DESCRIPTION OF THE DRAWING The foregoing and other objects and featuresof the present invention will be more readily understood from thefollowing detailed description of an illustrative embodiment thereofwhen read with reference to the accompanying drawing in which:

FIG. 1 is a perspective view of a magnetic torque yarn tension device ofthe type described above, on which has been installed a yarn snag shieldin accordance with the principles of the invention and shows a typicalyarn loop suspended from the device;

FIG. 2 is the same perspective view as FIG. 1 but shows the manner inwhich the yarn loop is eliminated and the manner in which the yarnrides-up the conical surface of the snag shield of this invention inresponse to tension applied to the yarn when movement of the yarn isinitiated; and

FIG. 3 is the same perspective view as FIGS. 1 and 2 but shows themanner in which the yarn is repositioned to the proper running positionabout the periphery of the rotatable capstan of the yarn tension deviceby the yarn snag shield of the invention.

DETAILED DESCRIPTION An illustrative embodiment of a yarn snag shield 10in accordance with the principles of the invention is shown in FIGS. 1through 3 of the drawing suspended below base plate 11 of a magnetictorque yarn tension device 12. Tension device 12 may be a tension deviceof the type described in the above-identified United States patents ofR. H. Roughsedge or J. E. Bancroft, or may be any device having arotatable wheel or capstan such as capstan 13 of tension device 12 aboutwhich a yarn to be controlled is positioned.

As shown in the drawing, tension device 12 is secured to mounting rod 14by bracket 15 and screw 16. Capstan 13 has a central shaft 17 aboutwhich it rotates. Shaft 17 is supported on suitable bearings (not shown)on base plate 11. Concentric with shaft 17 and secured to base plate 11inside capstan 13 is-an electrornagnetic field member (not visible indrawing) which produces the magnetic flux that interacts with a rotorconcentrically mounted on the inner surface of capstan 13, and thus notvisible in the drawing, to produce a drag, or braking force, opposingrotation of capstan 13.

Yarn 18, the tension of which is to be controlled, is threaded throughan inlet yarn guide 19, passed around the periphery of capstan 13 in aclockwise direction, and threaded out through an outlet yarn guide 20 ina direction from right to left as shown in the. drawing. When yarn 18 isin its proper running position. aroundcapstan 13, it follows the dottedpath 18' shown in FIG. 1. However, when an overrun condition occurs, asdescribed above, or when yarn 18,is improperly handled, it may form in aloop 18" suspended from tension device 12 as shown in FIG. 1. i

As shown in the drawing, snag shield 10, in accordance with the presentinvention, is an inverted coneshaped member suspended below base plate11 and is substantially coterminous therewith at its base. Shield 10 maybe fabricated of any suitable material, such as plastic or metal, andsecured to base plate 11 ina manner well known in the art. The surfaceof shield'10 extends from the apex 10 to and is substantially flush withthe surface of base plate 11, which in turn is flush with the peripheryof capstan 13, thus providing an uninterrupted path for yarn loops suchas 18" to traverse when sliding up the conical surface of shield 10 ontothe periphery of capstan 13.

As illustrated in the drawing, capstan 13 is positioned in a cylindricalcavity in base plate 11 and thus shield 10 is made coterminous with baseplate 11 to provide the uninterrupted path for the yarn loop 18 totraverse. In some types of yarn tension devices, the capstan is notpositioned in a depression and, accordingly, in accordance with theprinciples of the present invention, shield 10 would be coterminous withthe capstan and extend to be substantially flush with the periphery ofthe capstan. I

Yarn shield 10 is not a right-circular cone, as the apex of shield 10 isoffset or displaced to the rear as viewed in the drawing, such that itis located behind the line of suspension of any yarn loop 18" that mayform in yarn '18. This will prevent such yarn loops from locating behindthe conical shield 10 when tension is applied to yarn 18 in response tomovement of the yarn. Thus, shield 10 prevents yarn 18 from snagging onthe lower side of base plate 11 when yarn movement is initiated.

FIGS. 2 and 3 illustrate the manner in which shield 10 automaticallyguides yarn 18, which has formed into a loop 18" to the proper runningposition around the periphery of capstan 13. As shown in FIG. 2, whenmovement of the left-hand end of yarn 18 is initiated, the slack yarnforming loop 18 is taken up and loop 18" rides up the surface of shield10. As further slack in loop 18" is removed, loop 18" becomes smaller,and finally yarn 18 clears shield 10 on base plate 11 in the mannershown in FIG. 3. When all of the slack forming loop 18" is removed, yarn18 will once again be positioned about the periphery of capstan 13 asillustrated by dotted line 18' in FIG. 1.

In the manner described above and illustrated in the drawing, shield 10not only prevents a yarn loop from snagging on base plate 11, but alsoautomatically repositions yarn 18 to the proper running position aroundthe periphery ofcapstan 13 when movement of the yarn is initiated.

It is to be understood that the above-described embodiment isillustrative only of the principles of the present invention. Numerousother arrangements may be devised by those skilled in the art withoutdeparting from the spirit and scope of the invention.

What is claimed is:

1. In a yarn tension device comprising a support member, a capstanmounted on said support member for rotation about a vertical axis inresponse to longitudinal movement of a yarn trained about the peripherythereof and means for applying a force to said capstan to resist saidrotation and thereby impart tension to said yarn, the inventioncomprising a yarn snag shield comprising an inverted cone-shaped membersuspended below said capstan with the base of said member substantiallycoterminous with at least a portion of said capstan to prevent a yarnloop suspended from said tension device from snagging on said supportmember, said shield further including means for automaticallyrepositioning said yarn loop to a position trained about the peripheryof said capstan in response to the initiation of longitudinal movementof said yarn, said means for repositioning said yarn loop comprising theconical surface of said member.

2. The yarn snag shield defined in claim 1 wherein the apex of saidinverted cone-shaped member is displaced to the rear of the line ofsuspension of said yarn loop suspended from said tension device wherebysaid yarn loop will ride-up the conical surface of said member and ontothe periphery of said capstan in response to the initiation oflongitudinal movement of said yarn.

3. In combination with a yarn tension device for controlling the tensionof a moving yarn, means for preventing a yarn loop suspended from saiddevice from snagging on the structure supporting said device andconcomitantly automatically positioning said yarn loop to the correctrunning position on said device in response to the initiation ofmovement of said yarn, said tension device comprising:

a base plate,

a capstan positioned in a cylindrical cavity in the upper surface ofsaid base plate and extending upwardly therefrom,

said yarn being trained about the periphery of the portion of saidcapstan extended above said base plate whereby said capstan rotatesabout a vertical axis in response to movement of said yarn,

and wherein said means for preventing a yarn loop from snagging andconcomitantly automatically positioning said yarn loop comprises:

a yarn snag shield afiixed to the lower surface of said base plate andextending downwardly therefrom, said shield being substantiallycoterminous with said base plate.

4. The combination defined in claim 3 wherein said yarn snag shieldcomprises an inverted cone-shaped member affixed to the lower surface ofsaid base plate, with the base of said cone-shaped member beingsubstantially coterminous with said base plate and with the apex of saidmember extending downwardly.

5. The combination defined in claim 4 wherein said apex of saidcone-shaped member is oifset behind the line of suspension of said yarnloop suspended from said tension device whereby said yarn loop willride-up the conical surface of said member and onto the periphery 5/1888Cumming 2421S5 5/ 1962 Bancroft.

STANLEY N. GILREATH, Primary Examiner

